


Kara's Big Sister

by soundoftheunderground



Category: Supergirl (TV 2015)
Genre: F/F
Language: English
Status: In-Progress
Published: 2021-03-12
Updated: 2021-03-14
Packaged: 2021-03-18 23:14:04
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,499
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29990283
Author URL: https://archiveofourown.org/users/soundoftheunderground/pseuds/soundoftheunderground
Summary: She’s almost fourteen, and people start to mention college and scholarships, and the word potential is used a lot when adults discuss her talent.But then Kara arrives, and things change. Her parents don’t have the time to drive her to practice anymore, and they don’t go to her games because Kara can’t handle the noise.Not a HSAU. Alex has spent her whole life not being still, and almost half of it being Kara's Big Sister. She has the weight of the world on her shoulders and nobody to share it with. But then, Maggie.
Relationships: Alex Danvers/Maggie Sawyer
Comments: 4
Kudos: 44





	1. Chapter 1

**Author's Note:**

> Hola amigos. This is my first foray into the Supergirl writing fandom, so feel free to let me know what you think or what you'd like to see/read as we move forward with the story. I hope you enjoy :)

Her dad first starts getting her into sports because no matter where she is or what she’s doing, she can never seem to stay still for long. If it’s not her fingers tapping a random rhythm on whatever surface is closest, it’s her leg twitching up and down at an almost frantic rate. Alex never notices what she’s doing until someone brings her attention to it, and even then she doesn’t stop for long.

The first sport her dad takes her to is soccer. She quickly gets the hang of it, and before long she’s the best defender in the league. She’s also one of the top goal-scorers too, though that’s not supposed to be her job. Her coach loves her, but her teammates don’t. Her lack of interest in making friends and natural abilities alienate her pretty quickly. She only stays for one season before it becomes too much.

So they try softball next. Her hand-eye coordination stands her in good stead, and she has no issues picking up the rules. She once again establishes herself as a competitor early on, though she has the same issues as before. She’s too competitive, too focused, too successful to endear herself to her fellow players, who don’t bother trying to invite her into the fold after the first couple of games. She lasts half a season, and then quietly asks her dad if they can try something new.

Her dad offers her a sad smile and a nod, and doesn’t make her go to another practice or game.

After softball comes basketball. Her height helps her, and she actually manages to make friends with a couple of the girls. For a while, things are great. She goes to practice twice a week, plays a couple of games a month, and even gets invited to sleepovers and movie nights with her teammates. She once again becomes a great offensive and defensive weapon, and this time her team supports her skills. She thrives, and it’s not long before she makes a name for herself. She’s almost fourteen, and people start to mention college and scholarships, and the word _potential_ is used a lot when adults discuss her talent.

But then Kara arrives, and things change. Her parents don’t have the time to drive her to practice anymore, and they don’t go to her games because Kara can’t handle the noise. The sleepovers slow, and then stop altogether, because she has a sister now. Her job is to spend time with her, help her to get used to life on earth.

Eventually she has to let basketball go so she can focus her attention on her new sister. The time she spent having fun with her friends is replaced with tense movie nights, or game nights, or some other kind of family bonding time. Only her parents rarely turn up for them, and if they do, their attention is focused on Kara. When they do shift their attention to Alex, it’s usually to scold her for not being friendly enough, or because her latest grades aren’t what they expected, or to suggest that she spend more time with Kara.

It’s a lot.

Too much, really. Alex is fifteen, but she feels like the weight of the world is on her shoulders. The twitching is back, only this time it’s worse. Agitation and anxiety make her even more antsy, make her feet itch with the need to run away.

She doesn’t, of course. She might dream about it, spend hours planning what she would do and where she would go, but she never goes through with it. She’s a big sister, so how could she?

Instead, she compromises. She starts leaving the house in the early morning to run along the beach, grateful for the time where she just gets to be Alex instead of Kara’s Big Sister.

It’s on one of these runs that she sees them. A group of teenagers of a similar age are floating amongst the waves, laughing and splashing as they lounge on surfboards. Alex stops and watches as they take turns catching waves, breath catching as she sees how carefree they all seem to be.

That weekend she uses her running away fund to buy herself a surfboard and wetsuit of her own. She doesn’t bother speaking to her parents first. She knows her dad used to surf, but they don’t really talk that much anymore. He’s always working, or trying to help Kara settle into life on earth. She doubts her mother will even notice.

She reads books and articles and watches videos, taking notes of how surfing works. She pauses during her runs and watches the teenagers and other strangers as they ride the waves, analysing how they move their bodies. Her body vibrates with the need to paddle out and try it for herself, but she decides to wait until everybody has left to go back and grab the board.

When she finally gets into the water for the first time, her heart is pounding. Her arms cut through the water easily enough, and she ducks her head and paddles through a couple of waves as she heads into deeper water, but she’s shaking. This isn’t like little league, or pee wee soccer. There’s no coach to tell her what to do. Her dad isn’t on the side-lines offering support. It’s just her, her board, and the waves.

Speaking of waves, there’s a promising one approaching. Alex takes a deep breath, prepares herself, and waits. One second passes, and then two. Her board starts to rise as the swell approaches, so she does what she’s seen everyone else doing. She paddles, hard. Three strokes, then four. On the seventh stroke she risks a glance behind her and sees that it’s time. She grabs the sides of her board, shifts her body, and goes for it.

Her knees pull up to her chest as she plants her feet, and she slowly loosens her grip so she’s crouched. Feeling a rush of adrenaline hit, she decides it’s all or nothing and stands straight up. Her arms are outstretched as she fights to keep her balance, and her knees are wobbly, but she stays up. She lets out a whoop of joy as she rides the wave, unable to hold in the strangled laugh that escapes.

For the first time since Kara arrived, she feels free.


	2. Just Another Day In The Commonwealth

**Notes for the Chapter:**

> This seems to have evolved into a Supergirl/Fallout 4 hybrid. Wasn't the plan, but I'm rolling with it. If you have any ideas as to who might be who, feel free to let me know :)
> 
> Also, this applies to SuperFriends and Vault Dwellers both - the story isn't going to follow the storylines of the show or the game. Aspects will be similar, but also, not really.
> 
> Yeehaw.

The world doesn’t look like it used to. Alex still finds herself looking around in wonder as she makes her way through the crumbling remains of what used to be National City. The skyscrapers have long since fallen to ruin, allowing the sun to blaze down in all its glory. Old roads have fallen into disrepair, riddled with potholes and deep cracks that make it uneven and perilous to walk on at times. The once bustling streets are empty, not another soul in sight. The only sound is the slow plodding of her boots as she patrols the area, stopping every so often to listen.

Her left hand swings seemingly casual at her side, though it is never more than a couple of inches from the tactical knife tucked into a secret pocket of her combat trousers. Her right is clutched around the heavily modded 10mm pistol that she carries with her everywhere. It might not look like much compared to monstrosities that many choose to carry, but it does the job marvellously when she needs it to. One of the perks of being an engineering whiz, she supposes.

At twenty seven, Alex has spent almost a decade in this new wasteland that they have come to call the Commonwealth. She may have emerged from the Vault a terrified teenager with no knowledge of what the world had become, but there’s no trace of that girl now. Instead, she stands tall and lean and hard, a veteran that many have learned to look at in respect, fear, or a combination of both.

As the overshadowed older sister of an alien with superpowers and a smile brighter than the sun, she kind of enjoys it. No matter what people say about Kara, this reputation she has earned all on her own.

 _Speaking of Kara_ , Alex thinks, _where the hell is she?_

She scans her surroundings for the hundredth time, listening for any signs of movement. Glancing down at her Pipboy, she confirms that she is indeed in the right place at the right time. Which, she obviously is. Alex doesn’t make mistakes. She can’t afford to.

She has spent the last three days following Kara and James in their quest to find a disgruntled former employee of The Institute. Scuttlebutt in Diamond City, the new downtown hub of National City residents aptly named after the baseball stadium it has been constructed within, alerted them to the potential story, and Kara being Kara had decided that she just had to find out for herself.

Which is how she has ended up here, in a rather precarious position, cooking under the high noon sun as she waits for her idiot sister and her idiot friend to return from their little detour into the old headquarters of CatCo. The message she’d received on her Pipboy said that it wasn’t dangerous, and they hadn’t wanted to wake Alex up.

Which, rude. How is she supposed to be able to do her job protecting her sister if said sister _keeps sneaking off like the idiot she clearly is._

Alex can feel sweat dripping down the back of her neck, but ignores the discomfort. She’ll be doing a lot more of it before the day is out, she knows. This new world is a hard once. It’s physically demanding, emotionally exhausting, and more often than not, painful.

The dull ache in her arm is testament to that fact. Glancing around once more to make sure nobody is sneaking up on her, Alex takes a few seconds to look down and take the injury in. It’s relatively minor compared to previous wounds, but constant use and frequent skirmishes means that it isn’t healing as quickly as she’d like. The stab wound is wrapped in gauze, but blood still seeps through, indicating that she has once again ripped open her stitches. Whoops.

It’s one of the many, many reminders of what it means to be Kara’s Big Sister. Not that she’d change it, of course. Fourteen years of companionship and shared experiences have resulted in a bond that she never could have imagined when she was first introduced to Kara so long ago.

They still fight of course. They fight over Kara’s constant desire to reveal her powers to the world, they fight over Alex’s impulsive reckless streak. They argue over who gets the last Fancy Lad Snack Cake even though they both know Kara will win and they argue about the fact that Alex conveniently has to leave Diamond City whenever Eliza comes to visit. But no matter how big or small the disagreement, the one thing that they can always agree on is that they are a team. Whether one agrees with the other or not, they will always have each other’s back.

‘Why do I feel like something bad is about to happen?’ Alex mutters to herself, as the hairs raise on her arms.

‘Probably because it is.’

‘ _Jesus Christ.’_ Alex curses, body swinging to face where her sister is now standing beside her. ‘I told you to stop doing that.’

‘You can tell me again later.’ Kara replies, grabbing Alex’s arm and dragging her out of the road. ‘Right now, we have to get out of here.’

Alex yanks her arm out of Kara’s grasp, even as she crouches to follow her. She turns off the safety on her pistol as she takes cover behind an old retail counter. Kara has already made herself as small as possible in the corner, her eyes focused on the spot Alex had been standing in previously. Alex opens her mouth, but Kara shakes her head and gestures to the road.

Taking the hint, Alex settles herself so she can just about peek around the corner of the counter, and waits. She can feel her heartbeat thundering in her ears, but ignores it.

A minute passes, then two.

Alex’s heart starts to steady, and a familiar calm settles over her when she hears people approaching. She glances over at where Kara is still focused on where they must be coming from, and is reminded of why she is doing this, why she is wandering this barren wasteland with a pistol in her hand and no less than seven other weapons stashed in various other places on her body.

She offers her sister a small smile when she catches her eye. Kara doesn’t hesitate to return it, though it’s a couple of megawatts dimmer than normal. Understandable, considering the fact that there are…seven raiders currently walking down the street, laughing and joking as they go.

‘Did you hear that Motorcyle Guy showed up again a couple weeks ago?’ One raider says, voice deep and gravelly.

‘Give it up, Samson.’ Another voice, this one belonging to a woman.

‘I swear it’s true.’ Samson (?) replies. ‘Will was telling me that he did a drive-by the Federal Stockpile, threw a couple of grenades, and then drove off again.’

‘And you choose to believe that guy?’ A third raider asks, incredulous. ‘That guy is constantly out of his mind on chems. I’m surprised he even knows his own name.’

‘I’m telling you guys,’ Samson insists, voice rising in frustration, ‘This guy is real, and he’s gunning for us. That’s the fourth attack in three months.’

‘I haven’t heard of any attacks.’ The second voice says, shrugging.

Alex holds her breath as the group draws parallel to where she and Kara are hiding, finger tightening on the trigger of her pistol. Her body tenses, itching to attack. These people are thugs, beating and robbing and killing innocent people just because they can. The world would be a much better place without them in it.

‘Alex, no.’ Kara whispers, shaking her head frantically.

Alex looks at her little sister and sighs, relaxing her muscles just slightly. One day, she’s going to be able to say no to that face, but today doesn’t seem to be that day. She offers the smallest of nods, and then stills.

The voices have stopped.

Getting a Very Bad Feeling is something that happens to Alex a lot, and it’s happening now. Very slowly, she turns back to peek around the counter, grip tightening on her weapon once more.

Barely ten feet away, fourteen scuffed boots are pointed directly at them.

‘Alex, yes.’ She murmurs, offering a silent apology to her sister as she fires off her first shot.

There’s a whoosh of air across her back as Kara flies past faster than the speed of sound, barely a blur in the corner of her eye.

Just another day in the Commonwealth.


End file.
